Heteroleptic tin (II) dialkoxides stabilized by intramolecular coordination Sn(OCH2CH2NMe2)(OR) (R = Me, Et, Pr, Bu, Ph). Synthesis, structure and catalytic activity in polyurethane synthesis

A straightforward method of synthesis of heteroleptic tin (II) alkoxides stabilized by one intramolecular coordination bond was developed. Addition of one equivalent of dimethylamino ethanol to diamide Sn(N(SiMe₃)₂)₂ (5) yields alkoxy-amido derivative Sn(OCH₂CH₂NMe₂)(N(SiMe₃)₂) (2). Further addition of alcohol leads to corresponding heteroleptic dialkoxides Sn(OCH₂CH₂NMe₂)(OR) (R = Me (6), Et (7), ⁱPr (8), ^tBu (9), Ph (10)). Catalytic activity of tin (II) compounds in polyurethane formation was tested.     

Synthesis, characterization, and substituent effects of mononuclear ruthenium complexes [RuCl(CO)(PMe3)3(CHCH-C6H4-R-p)] (R = H, CH3, OCH3, NO2, NH2, NMe2)

A series of mononuclear ruthenium complexes [RuCl(CO)(PMe₃)₃(CHCH-C₆H₄-R-p)] (R = H (2a), CH₃ (2b), OCH₃ (2c), NO₂ (2d), NH₂ (2e), NMe₂ (2f)) has been prepared. The respective products have been characterized by elemental analyses, NMR spectrometry, and UV-Vis spectrophotometry. The structures of complexes 2c and 2d have been established by X-ray crystallography. Electrochemical studies have revealed that electron-releasing substituents facilitate monometallic ruthenium complex oxidation, and the substituent parameter values (σ) show a strong linear correlation with the anodic half-wave or oxidation peak potentials of the complexes.     

Branched and dendritic metallo-carbosiloxanes with OCH2PPh2MLn end-grafted units

A straightforward method for the preparation of metallo carbosiloxanes of type Si(OCH₂CH₂CH₂SiMe₂[OCH₂PPh₂M(CO)_n])₄ (n = 3, M = Ni, 7a; n = 4, M = Fe, 7b; n = 5: M = Mo, 7c; M = W, 7d), Si(OCH₂CH₂CH₂SiMe[OCH₂PPh₂Ni(CO)₃]₂)₄ (8) and Me₂Si(OCH₂CH₂CH₂SiMe[OCH₂PPh₂Ni(CO)₃]₂)₂ (11) is described. The reaction of Si(OCH₂CH₂CH₂SiMeXCl)₄ (1: X = Me, 2: X = Cl) or Me₂Si(OCH₂CH₂CH₂SiMeCl₂)₂ (9) with HOCH₂PPh₂ (3) produces Si(OCH₂CH₂CH₂SiMe₂(OCH₂PPh₂))₄ (4), Si(OCH₂CH₂CH₂SiMe(OCH₂PPh₂)₂)₄ (5) or Me₂Si(OCH₂CH₂CH₂SiMe(OCH₂PPh₂)₂)₂ (10) in presence of DABCO. Treatment of the latter molecules with Ni(CO)₄ (6a), Fe₂(CO)₉ (6b), M(CO)₅(Thf) (6c: M = Mo; 6d: M = W), respectively, gives the title compounds 7a-7d, 8 and 11 in which the PPh₂ groups are datively bound to a 16-valence-electron metal carbonyl fragment.The formation of analytical pure and uniform branched and dendritic metallo carbosiloxanes is based on elemental analysis, and IR, ¹H, ¹³C{¹H}, ²⁹Si{¹H} and ³¹P{¹H} NMR spectroscopic studies. In addition, ESI-TOF mass spectrometric studies were carried out.     

New versatile organyltellurium(IV) halides: Synthesis and X-ray structural features of the telluronium tellurolate salts [PhTe(CH3)2]2[TeX6] (X = Cl, Br) and [Ph3Te][PhTeX4] (X = Cl, Br, I)

TeX₄ (X = Cl, Br) react in HCl/HBr with [Ph(CH₃)₂Te]X (X = Cl, Br) to give [PhTe(CH₃)₂]₂[TeCl₆] (1) and [PhTe(CH₃)₂]₂[TeBr₆] (2). The reaction of PhTeX₃ (X = Cl, Br, I) in cooled methanol with [(Ph)₃Te]X (X = Cl, Br, I) leads to [Ph₃Te][PhTeCl₄] (3), [Ph₃Te][PhTeBr₄] (4) and [Ph₃Te][PhTeI₄] (5). In the lattices of the telluronium tellurolate salts 1 and 2, octahedral TeCl₆ and TeBr₆ dianions are linked by telluronium cations through Te?Cl and Te?Br secondary bonds, attaining bidimensional (1) and three-dimensional (2) assemblies. The complexes 3, 4 and 5 show two kinds of Te?halogen secondary interactions: the anion-anion interactions, which form centrosymmetric dimers, and two identical sets of three telluronium-tellurolate interactions, which accomplish the centrosymmetric fundamental moiety of the supramolecular arrays of the three compounds, with the tellurium atoms attaining distorted octahedral geometries. Also phenyl C-H?halogen secondary interactions are structure forming forces in the crystalline structures of compounds 3, 4 and 5.     

Oxime-substituted NCN-pincer palladium and platinum halide polymers through non-covalent hydrogen bonding (NCN = [C6H2(CH2NMe2)2-2,6])

The oxime-substituted NCN-pincer molecules HONCH-1-C₆H₃(CH₂NMe₂)₂-3,5 (2a) and HONCH-4-C₆H₂(CH₂NMe₂)₂-2,6-Br-1 (2b) were accessible by treatment of the benzaldehydes H(O)C-4-C₆H₃(CH₂NMe₂)₂-3,5 (1a) and H(O)C-4-C₆H₂(CH₂NMe₂)₂-2,6-Br-1 (1b) with an excess of hydroxylamine. In the solid state both compounds are forming polymers with intermolecular O-H?N connectivities between the Me₂NCH₂ substituents and the oxime entity of further molecules of 2a and 2b, respectively. Characteristic for 2a and 2b is a helically arrangement involving a crystallographic 2₁ screw axis of the HONCH-1-C₆H₃(CH₂NMe₂)₂-3,5 and HONCH-4-C₆H₂(CH₂NMe₂)₂-2,6-Br-1 building blocks.The reaction of 2b with equimolar amounts of [Pd₂(dba)₃ · CHCl₃] (3) (dba = dibenzylidene acetone) or [Pt(tol)₂(SEt₂)]₂ (4) (tol = 4-tolyl) gave by an oxidative addition of the C-Br unit to M coordination polymers with a [(HONCH-4-C₆H₂(CH₂NMe₂)₂-2,6)MBr] repeating unit (5: M = Pd, 6: M = Pt). Complexes 5 and 6 are in the solid state linear hydrogen-bridged polymers with O-H?Br contacts between the oxime entities and the metal-bonded bromide.     

Synthesis, structures and preliminary biological screening of bis(diphenyl)chlorotin complexes and adducts: Ph2ClSn-CH2-R-CH2-SnClPh2, R = p-C6H4, CH2CH2

The reaction between ClCH₂-R-CH₂Cl, R = p-C₆H₄, and [Ph₃Sn]⁻Li⁺ yields Ph₃Sn-CH₂-R-CH₂-SnPh₃ (1) in high yield. The related known compound R = CH₂CH₂ (1a) is synthesized by the reaction of the di-Grignard reagent BrMg(CH₂)₄MgBr with two equivalents of Ph₃SnCl. Cleavage of a single Sn-Ph group at each tin centre of both compounds using HCl/Et₂O yields the corresponding bis-chlorostannanes Ph₂ClSn-CH₂-R-CH₂-SnClPh₂, R = (CH₂)₄ (2) and R = C₆H₄ (3), respectively. Compounds 1, 2 and 3 are crystalline solid materials and their single crystal X-ray structures are reported. In the solid state both 2 and 3 form self-assembled ladder structures involving alternating intermolecular Cl-Sn?Cl and Cl?Sn-Cl bonded chains at both ends of the distannanes with 5-coordinate tin atoms. Recrystallization of 3 from CH₂Cl₂ in the presence of DMF yields the bis-DMF adduct (4) in which no self-assembled structures were noted. Evaluation of the chlorostannanes 2 and 3 against a suite of bacteria, Staphylococcus aureus, Escherichia coli and Photobacterium phosphoreum is reported and compared to the related mono-chlorostannanes Ph₂(CH₃)SnCl and Ph₂(PhCH₂)SnCl.     

New stable germylenes, stannylenes, and related compounds: 6. Heteroleptic germanium(II) and tin(II) compounds [(SiMe3)2N-E-OCH2CH2NMe2]n (E = Ge, n = 1; Sn, n = 2): synthesis and structure

New stable heteroleptic germanium(II) and tin(II) compounds [(SiMe₃)₂N-E¹⁴-OCH₂CH₂NMe₂]_n (E¹⁴ = Ge, n = 1 (1), Sn, n = 2 (2)) have been synthesized and their crystal structures have been determined by X-ray diffraction analysis. While compound 1 is monomer stabilized by intramolecular Ge ← N coordination, compound 2 is associated to dimer via intermolecular dative Sn ← O interactions.     

Formation and structural characterization of mercury complexes from Te(R)CH2SiMe3 (R = Ph, CH2SiMe3) and HgCl2

The reaction of HgCl₂ and Te(R)CH₂SiMe₃ [R = CH₂SiMe₃ (1), Ph (2)] in ethanol yielded a mononuclear complex [HgCl₂{Te(R)CH₂SiMe₃}₂] (R = Ph, 3a; R = CH₂SiMe₃, 3b). The recrystallization of 3a or 3b from CH₂Cl₂ produced a dinuclear complex [Hg₂Cl₂(μ-Cl)₂{Te(R)CH₂SiMe₃}₂] (R = Ph, 4a; R = CH₂SiMe₃, 4b). When 3a was dissolved in CH₂Cl₂, the solvent quickly removed, and the solid recrystallized from EtOH, a stable ionic [HgCl{Te(Ph)CH₂SiMe₃}₃]Cl·2EtOH (5a·2EtOH) was obtained. Crystals of [HgCl₂{Te(CH₂SiMe)₂}]·2HgCl₂·CH₂Cl₂ (6b·2HgCl₂·CH₂Cl₂) were obtained from the CH₂Cl₂ solution of 3b upon prolonged standing. The complex formation was monitored by ¹²⁵Te-, and ¹⁹⁹Hg NMR spectroscopy, and the crystal structures of the complexes were determined by single crystal X-ray crystallography.     

New stable germylenes, stannylenes, and related compounds. 5. Germanium(II) and tin(II) azides [N3-E-OCH2CH2NMe2]2 (E = Ge, Sn): synthesis and structure

New stable azido derivatives of divalent germanium and tin [N₃-E¹⁴-OCH₂CH₂NMe₂]₂ (E¹⁴ = Ge (1), Sn (2)) have been synthesized by use of the β-dimethylaminoethoxy ligand that forms the intramolecular E¹⁴ ← N coordination bond. Their crystal structures have been determined by X-ray diffraction analysis. Compounds 1 and 2 are centrosymmetric dimers via two intermolecular dative E¹⁴ ← O interactions with essentially linear monodentate azide ligands. The dominant canonical form of the E¹⁴-azide moieties is E¹⁴-N-NN.     

Ate complexes of Ge(II) and Sn(II) with bidentate ligands [LiE(OCH2CH2NMe2)3]2 (E=Ge, Sn): synthesis and structure

The reaction of equimolar quantities of LiOCH₂CH₂NMe₂ and E¹⁴(OCH₂CH₂NMe₂)₂ (E¹⁴=Ge, Sn) in ether yielded new ate complexes [LiE¹⁴(OCH₂CH₂NMe₂)₃]₂ (E¹⁴=Ge (1), Sn (2)) with bidentate ligands. The compounds 1 and 2 are white crystalline substances which are highly soluble in THF and pyridine and very sensitive to the traces of oxygen and moisture. The structures of these compounds are studied by X-ray diffraction analysis. The ate complexes 1 and 2 are powerful nucleophiles and may be employed as ligands (neutral) in the coordination chemistry of the transition metals. The electronegative O-substituents at the divalent E¹⁴ atoms render them less oxidizable than alkyl- or aryl-substituted derivatives, and the bidentate ligands, owing to intramolecular donor-acceptor interactions, make them more thermodynamically stable compared to monodentate ligands.     

Novel sandwich complexes of zirconium [C9H5(SiMe3)2](C5Me4R)ZrCl2 (R = CH3, CH2CH2NMe2): Synthesis and reduction behavior

Novel half-sandwich [C₉H₅(SiMe₃)₂]ZrCl₃ (3) and sandwich [C₉H₅(SiMe₃)₂](C₅Me₄R)ZrCl₂ (R = CH₃ (1), CH₂CH₂NMe₂ (2)) complexes were prepared and characterized. The reduction of 2 by Mg in THF lead to (η⁵-C₉H₅(SiMe₃)₂)[η⁵:η²(C,N)-C₅Me₄CH₂CH₂N(Me)CH₂]ZrH (7). The structure of 7 was proved by NMR spectroscopy data. Hydrolysis of 2 resulted in the binuclear complex ([C₅Me₄CH₂CH₂NMe₂]ZrCl₂)₂O (6). The crystal structures of 1 and 6 were established by X-ray diffraction analysis.     

Quantum chemical study of ethylene addition to group-7 oxo complexes MO2(CH3)(CH2) (M = Mn, Tc, Re)

Quantum chemical calculations using DFT at the B3LYP level have been carried out for the reaction of ethylene with the group-7 compounds ReO₂(CH₃)(CH₂) (Re1), TcO₂(CH₃)(CH₂) (Tc1) and MnO₂(CH₃)(CH₂) (Mn1). The calculations suggest rather complex scenarios with numerous pathways, where the initial compounds Re1-Mn1 may either engage in cycloaddition reactions or numerous addition reactions with concomitant hydrogen migration. There are also energetically low-lying rearrangements of the starting compounds to isomers which may react with ethylene yielding further products. The [2 + 2]_Re,C cycloaddition reaction of the starting molecule Re1 is kinetically and thermodynamically favored over the [3 + 2]_C,O and [3 + 2]_O,O cycloadditions. However, the reaction which leads to the most stable product takes place with initial rearrangement to the dioxohydridometallacyclopropane isomer Re1a that adds ethylene with concomitant hydrogen migration yielding Re1a-1. The latter reaction has a slightly higher barrier than the [2 + 2]_Re,C cycloaddition reaction. The direct [3 + 2]_C,O cycloaddition becomes more favorable than the [2 + 2]_M,C reaction for the starting compounds Tc1 and Mn1 of the lighter metals technetium and manganese but the calculations predict that other reactions are kinetically and thermodynamically more favorable than the cycloadditions. The reactions with the lowest activation barriers lead after rearrangement to the ethyl substituted dioxometallacyclopropanes Tc1a-1 and Mn1a-1. The manganese compound exhibits an even more complex reaction scenario than the technetium compounds. The thermodynamically most stable final product of ethylene addition to Mn1 is the ethoxy substituted metallacyclopropane Mn1a-2 which has, however, a high activation barrier.     

Organoselenium(II) and selenium(IV) compounds containing 2-(Me2NCH2)C6H4 moieties: solution behavior and solid state structure

The cleavage of the Se-Se bond in [2-(Me₂NCH₂)C₆H₄]₂Se₂ (1) was achieved by treatment with SO₂Cl₂ (1:1 molar ratio) or elemental halogens to yield [2-(Me₂NCH₂)C₆H₄]SeX [X = Cl (2), Br (3), I (4)]. Oxidation of 1 with SO₂Cl₂ (1:3 molar ratio) gave [2-(Me₂NCH₂)C₆H₄]SeCl₃ (5). [2-(Me₂NCH₂)C₆H₄]SeS(S)CNR₂ [R = Me (6), Et (7)] were prepared by reacting [2-(Me₂NCH₂)C₆H₄]SeBr with Na[S₂CNR₂] · nH₂O (R = Me, n = 2; R = Et, n = 3). The reaction of 3 with K[(SPMe₂)(SPPh₂)N] resulted in isolation of [2-(Me₂NCH₂)C₆H₄]Se-S-PMe₂N-PPh₂S (8). The compounds were characterized by solution NMR spectroscopy (¹H, ¹³C, ³¹P, ⁷⁷Se, 2D experiments). The solid-state molecular structures of 2, 4-8 were established by single crystal X-ray diffraction. All compounds are monomeric, with the N atom of the pendant CH₂NMe₂ arm involved in a three-center-four-electron N?Se-X (X = halogen, S) bond. This results in a T-shaped coordination geometry for the Se(II) atom in 2, 4, 6-8. In 5, the Se(IV) atom achieves a square pyramidal coordination in the mononuclear unit. Loosely connected dimers are formed through intermolecular Se?Cl interactions (3.40 Å); the overall coordination geometry being distorted octahedral. In all compounds hydrogen bonds involving halide or sulfur atoms generate supramolecular associations in crystals.     

Various silyl-substituted cyclopentadienyl titanium complexes [CpSi(CH3)2X]TiCl3 as catalysts for syndiotactic polystyrene

Three silyl-substituted titanium trichloride complexes [CpSi(CH₃)₂X]TiCl₃ [X=Cl(1), Me(2), PhOMe(3)] were tested as catalyst precursors for the syndiospecific polymerization of styrene. The catalytic activity increased in the order 1 > 2 > 3. The highest activity was 2.42 × 10⁷ g s-PS/mol Ti mol S h using complex 1/MAO catalytic system at molar ratio of Al/Ti=2000. The effects of variation on polymerization temperature and Al/Ti ratio on the polymerization of styrene were also studied.     

Synthesis and characterization of new silicon-centred tin-dendrimers Si[CH2CH2SnR3]4. Single-crystal X-ray structure of the tetrahydrofuran adduct of tetrakis[2-(tribromostannyl)ethyl]silane

A series of novel first-generation silicon-centred tin dendrimers Si(CH₂CH₂SnR₃)₄ [R = CH₃ (3), ⁱBu (4), CCCH₃ (5), C₆H₄CH₃-4 (6), C₆H₄OCH₃-4 (7), (CH₂)₄OCH₂CH₂OCH₃ (8), CH₂SiMe₃ (9)] was prepared by the reaction of Si(CH₂CH₂SnBr₃)₄ (2) with the appropriate Grignard reagent or LiCH₂SiMe₃ in tetrahydrofuran. The new compounds were characterized by multinuclear NMR studies (¹H, ¹³C, ¹¹⁹Sn), mass spectrometry (MALDI-TOF, EI) and elemental analyses. The molecular structure of Si[CH₂CH₂SnBr₃(THF)₂]₂[CH₂-CH₂SnBr₃(THF)]₂ (2a) was determined by single-crystal X-ray diffraction.     

Mixed-metal single-molecule magnets: Syntheses, structure, and magnetic properties of [Mn8Fe4O12(O2CR)16(H2O)4] (R = CH2Cl, CH2Br, CHCl2)

Three mixed-metal single-molecule magnets containing [Mn₈Fe₄O₁₂]¹⁶⁺ cores are synthesized and characterized. The reaction of FeCl₂·4H₂O with KMnO₄ and RCOOH (R = CH₂Cl, CH₂Br) in H₂O gives [Mn₈Fe₄O₁₂(O₂CR)₁₆(H₂O)₄] (R = CH₂Cl (1), CH₂Br (2)) in yields of 43% and 40%, respectively. Treatment of complex 1 with an excess of CHCl₂COOH in CH₂Cl₂ gives [Mn₈Fe₄O₁₂(O₂CCHCl₂)₁₆(H₂O)₄]·CH₂Cl₂·10H₂O (3·CH₂Cl₂·10H₂O) in a yield of 83%. The X-ray structure analysis reveals that all three complexes consist of a trapped-valence dodecanuclear core comprising 4Mn^III, 4Fe^III, and 4Mn^IV ions. DC magnetic susceptibility and magnetization measurements indicate that all three complexes exhibit intramolecular antiferromagnetic interaction, resulting in an S = 4 ground state. In addition, frequency-dependent out-of-phase AC magnetic susceptibility signals at low temperature for complexes 1, 2, and 3 are indicative of their single-molecule magnetism behavior.     

Reactions of Mo(II)-tetraphosphine complex [MoCl2{meso-o-C6H4(PPhCH2CH2PPh2)2}] with a series of small molecules

Reactions of Mo(II)-tetraphosphine complex [MoCl₂(κ⁴-P4)] (2; P4 = meso-o-C₆H₄(PPhCH₂CH₂PPh₂)₂) with a series of small molecules have been investigated. Thus, treatment of 2 with alkynes RCCR′ (R = Ph, R′ = H; R = p-tolyl, R′ = H; R = Me, R′ = Ph) in benzene or toluene gave neutral mono(alkyne) complexes [MoCl₂(RCCR′)(κ³-P4)] containing tridentate P4 ligand, which were converted to cationic complexes [MoCl(RCCR′)(κ⁴-P4)]Cl having tetradentate P4 ligand upon dissolution into CDCl₃ or CD₂Cl₂. The latter complexes were available directly from the reactions of 2 with the alkynes in CH₂Cl₂. On the other hand, treatment of 2 with 1 equiv. of XyNC (Xy = 2,6-Me₂C₆H₃) afforded a seven-coordinate mono(isocyanide) complex [MoCl₂(XyNC)(κ⁴-P4)] (7), which reacted further with XyNC to give a cationic bis(isocyanide) complex [MoCl(XyNC)₂(κ⁴-P4)]Cl (8). From the reaction of 2 with CO, a mono(carbonyl) complex [MoCl₂(CO)(κ⁴-P4)] (9) was obtained as a sole isolable product. Reaction of 9 with XyNC afforded [MoCl(CO)(XyNC)(κ⁴-P4)]Cl (10a) having a pentagonal-bipyramidal geometry with axial CO and XyNC ligands, whereas that of 7 with CO resulted in the formation of a mixture of 10a and its isomer 10b containing axial CO and Cl ligands. Structures of 7 and 9 as well as [MoCl(XyNC)₂(κ⁴-P4)][PF₆](8′) and [MoCl(CO)(XyNC)(κ⁴-P4)][PF₆] (10a′) derived by the anion metathesis from 8 and 10a, respectively, were determined in detail by the X-ray crystallography.     

Synthesis of novel terdentate N,C,N′-coordinated butyltin(IV) complexes and their redistribution reactions with SnCl4

The Sn(IV) butyl complexes [Bu_nSnCl_3 − n(NCN)] (NCN = [C₆H₃(CH₂NMe₂)₂-2,6]⁻, n = 1 (1), 2 (2), 3 (3)) were prepared. Spectroscopic analysis of 1-3 by ¹H and ¹¹⁹Sn NMR gave evidence for the presence of intramolecular N → Sn interactions in solution. The molecular structure of 1, as determined by a single-crystal X-ray diffraction study, revealed that it contained a six-coordinate Sn(IV) center with intramolecular N → Sn coordination of both ortho-amine substituents. Addition of SnCl₄ to 1 resulted in the isolation of the HCl adduct [BuSnCl₃(NCN⁺H)] (6). Reactions of 2 and 3 with SnCl₄ each resulted in the HCl salt [SnCl₄(NCN⁺H)] (8) and the corresponding butyltin chloride, Bu₂SnCl₂ and Bu₃SnCl, respectively. The formation of HCl adducts 6 and 8 was ascribed to transfer of the NCN ligand to SnCl₄ and the presence of HCl (from partial hydrolysis of the product or SnCl₄ during the work up procedure). The molecular structures of 6 and 8 have been determined through single-crystal X-ray diffraction and revealed the presence of a [BuSnCl₃(aryl)]⁻ or [SnCl₄(aryl)]⁻ stannate anion, respectively, with in each case one coordinated ortho-amine function and one protonated amine moiety involved in N-H?Cl-Sn hydrogen bonding in both compounds (2.14 Å for 6 and 2.18 Å for 8).     

Synthesis and coordinating properties of the facultative Sb2O- and As2O-donor ligands O{(CH2)2ER2}2 (E = Sb or As; R = Ph or Me)

The new mixed Sb₂O-donor ligands O{(CH₂)₂SbR₂}₂ (R = Ph, 1; R = Me, 2) with flexible backbones have been prepared in good yields as air-sensitive oils from reaction of NaSbR₂ with 0.5 mol equivalents of O(CH₂CH₂Br)₂ in thf solution. The As₂O-donor analogues, O{(CH₂)₂AsR₂}₂ (R = Ph, 3; R = Me, 4) were obtained similarly from LiAsPh₂ or NaAsMe₂, respectively and O(CH₂CH₂Br)₂, although ligand 4 appears to be considerably less stable with respect to C-O bond fission under some conditions than the other ligands. Using O(CH₂CH₂Cl)₂ leads only to partial substitution by the SbPh₂⁻ or AsPh₂⁻ nucleophile. These ligands behave as bidentate chelating Sb₂- or As₂-donors in the distorted tetrahedral [M(L-L)₂]BF₄ (M = Cu or Ag; L-L = 1-4) on the basis of solution ¹H and ⁶³Cu NMR spectroscopic studies, mass spectrometry and microanalyses. Crystal structures of three representative examples with Cu(I) and Ag(I) confirm the distorted tetrahedral Sb₄ or As₄ coordination at the metal and allow comparisons of geometric parameters. The crystallographic identification of an unexpected Cu(I)-Cu(I) complex, [Cu₂{Me₂As(CH₂)₂OH}₃](BF₄)₂, obtained as a by-product via C-O bond fission within ligand 4 is also reported. The distorted octahedral [RhCl₂(L-L)₂]Cl and the distorted square planar cis-[PtCl₂(L-L)] (L-L = 1 or 2) are also described. The ether O atoms are not involved in coordination to the metal ion in any of the late transition metal complexes isolated.     

Synthesis and characterisation of six Fe(II or III), Co(II) or Zr(IV) complexes containing the ligand [CH(SiMe2R)P(Ph)2NSiMe3] (R = Me, NEt2) and of [Co{N(SiMe3)C(Ph)C(H)P(Ph)2NSiMe3}2]

The C,N-(trimethylsilyliminodiphenylphosphoranyl)silylmethylmetal complexes [Fe(L)₂] (3), [Co(L)₂] (4), [ZrCl₃(L)]·0.83CH₂Cl₂ (5), [Fe(L)₃] (6), [Fe(L′)₂] (7) and [Co(L′)₂] (8) have been prepared from the lithium compound Li[CH(SiMe₂R)P(Ph)₂NSiMe₃] [1a, (R = Me) {≡ Li(L)}; 1b, (R = NEt₂) {≡ Li(L′)}] and the appropriate metal chloride (or for 7, FeCl₃). From Li[N(SiMe₃)C(Ph)C(H)P(Ph)₂NSiMe₃] [≡ Li(L″)] (2), prepared in situ from Li(L) (1a) and PhCN, and CoCl₂ there was obtained bis(3-trimethylsilylimino- diphenylphosphoranyl-2-phenyl-N-trimethylsilyl-1-azaallyl-N,N′)cobalt(II) (9). These crystalline complexes 3-9 were characterised by their mass spectra, microanalyses, high spin magnetic moments (not 5) and for 5 multinuclear NMR solution spectra. The X-ray structure of 3 showed it to be a pseudotetrahedral bis(chelate), the iron atom at the spiro junction.